This project is directed toward the development of new statistical methodology for use in other areas of Institute research and human health research in general. To date interest has focused primarily on the field of genetic toxicology. In the last decade there has been heightened scientific attention paid to genetic toxicology because of the potential major role of mutagenesis in such diverse human health problems as cancer, aging and birth defects. Research in genetic toxicology is, relatively speaking, still in its infancy. The precise implications for humans of results from these studies are still vaguely understood. Exploration of the mechanistic role of mutagenesis in each individual health concern will be a lengthy and involved process. The need for sound, statistically based evaluation of genetic toxicity data as part of this learning process is recognized by most experts in the field. Design and analysis of individual assay experiments, together with efforts at assay validation, are areas in which statistical methodology contributions from this project have been notable. Emphasis in project research is shifting from in vitro to in vivo and human studies in recognition of the limitations of in vitro results to anticipate or predict effect in an intact mammal.